Google Inc's mysterious barges, which prompted fevered speculation about everything from offshore data centers to floating research labs, may serve a more prosaic role as upscale party venues and showrooms.

The multi-story vessels made out of stacked shipping containers, one moored in the San Francisco Bay and the other at the Portland, Maine harbor, are invitation-only luxury showrooms for Google's Glass wearable computers and other gadgets, according to local San Francisco TV station KPIX.

The structures will feature a top-floor "party deck," complete with "bars, lanais and other comforts," according to the report, which cited unnamed sources.

The existence of the floating barges surfaced last week, when technology website CNET theorized that the San Francisco vessel might be a floating data center that would house banks of computers. Google was granted a patent for a water-based data center in 2009.

Google has declined to comment on the matter, refusing even to acknowledge its affiliation with the vessels. But the executive director of the San Francisco Bay Conservation and Development Commission, Larry Goldzband, told Reuters his agency has had several meetings with Google officials about the barge in recent months.

Google has gone to great lengths to keep the details of the barges secret, with chain link fences and security guards encircling the pier where one of the barges is under construction at San Francisco's Treasure Island.

At least one Coast Guard employee has had to sign a non-disclosure agreement with the Internet giant, as did another person who would identify himself only as an inspector for a California government agency, Reuters reported earlier this week.

The project is being personally directed by Google co-founder Sergey Brin, according to KPIX. Brin heads up the Google division developing Google Glass, a cross between a mobile computer and eyeglasses that allows users to surf the Web and record video.

On Monday, Google said that it would expand the availability of the $1,500 Glass devices. Google has allowed a limited number of carefully selected early adopters to buy test versions of the device this year, and will now allow each of those customers to "invite" three friends to purchase the gadget.

The new showrooms could help Google build buzz for the wearable devices and its other hardware as it competes with more established hardware makers such as Apple Inc, which has hundreds of stylish retail outlets.

The Google shipping containers can be quickly assembled and disassembled, according to KPIX, allowing the showrooms to be transported by truck, rail or barge to destinations such as ski resorts and beaches.